1. Field of the Invention
This invention relates to a continuously operable hydraulic device utilizable in a continuous discharge pump, a hydraulically driven motor or the like.
2. Description of the Prior Art
As the continuously operable hydraulic device such for example as the continuous discharge pump, there have heretofore been developed ones of various types including (1) a screw pump in which a single thread screw is engaged between two double thread screws for rotation, (2) a vane type pump or a gear pump, (3) a duplex piston pump, (4) a three-throw plunger pump, and so forth. However, there are presented such problems that in the screw pump (1), although there is a linearity between the angle of rotation and the discharge flow rate, there occurs a leak because the seal is not a self-seal, whereby the screw pump is not suitable for delivering a very small quantity of fluid, in the vane pump and gear pump (2), the discharged fluid cannot avoid pulsations, in the duplex piston pump (3), when pistons are switched, there occurs a slight discontinuity, whereby the discharge flow rate cannot be held constant, and further, in the three-throw plunger pump (4), slight pulsations occur.
Now, the advanced technology requires the discharge pumps in which a discharge flow rate of a very small quantity can be controlled precisely. The applications thereof include (1) use in laboratories for the continuous operations on the very small quantities under high pressure, in the case of chromatograph, etc., (2) use in production factories for the purpose of continuously coating liquids such as chemical solutions, magnetic powder fluid dispersions onto articles continuously produced such as films, (3) use in chemical plants as pumps for continuously mixing at variable ratios, and (4) use in various factories for the computer control of liquids.
However, out of the above-described various conventional pumps, nothing has been developed to an extent where liquid of a very small quantity can be continuously discharged with high accuracy. Therefore, necessity has been voiced for a continuous discharge pump capable of discharging fluid of a very small quantity with a strict linearity in association with an angle of rotation of a driving source.
There are required not only the pumps capable of discharging fluid of a predetermined value under the operation of a driving source such as an electric motor as described above but also hydraulic driven motors for driving a driven component strictly through a predetermined angle by flowing fluid of a predetermined value. There has been needed a continuously operable hydraulic device capable of being applied to both pumps and motors.